World Resources Institute has open sourced and made available the base map files they use. This direct link is to the SVG downloads, which include files for Miller and winkel tripel projection, with a layer for disputed borders.
github.com/wri/wri-boun...

I used an arc diagram for this visualization on the live performance history of the band Fugazi, for which bands they played withe most. The arcs show which bands shared bills with eachother:
www.carniklirs.com/project/fugazi